The need for safe and efficient storage, delivery and transport of petrochemical or other types of fluids has driven much investment in engineering technology that has provided many solutions greatly improving these aspects of the processes involved. Current systems for storage and delivery of such fluids incorporate state-of-the-art electronic equipment for monitoring and controlling pump operations, and may utilize multiple product storage tanks supplying pump stations capable of serving several separate pumping operations and products simultaneously in a single load lane.
Such monitoring and control systems of current art are, in most applications, employed as separate monitoring and control units, and in a typical load lane for petroleum product transfer, for example, separate units for overfill prevention and vehicle static grounding verification are utilized that monitor various functions and conditions for safe operation, and can interrupt fluid flow if the conditions are not met. Separate sets of such units are used for monitoring sensors on the mobile tank, and for the base and delivery pump and valve operations, are typically mounted, sometimes with additional other monitoring or control units, on a loading rack located remotely from the pumping and metering area.
When an unsafe condition exists in either the fluid flow or grounding condition, pulsed signals are interpreted by the monitoring and control units, and command signals are sent to stop fluid flow by closing valves, disrupting the power to a pump or some other precautionary action. Interpretation by the monitoring and control units of the pulsed signals from sensors on the transport vehicle or pump station is based on preset information, some of which is input through a transport vehicle driver interface. The preset data assumes that mechanical valves and other equipment are in good condition and are properly tuned or adjusted and functioning as designed.
Whether a preset is of an older mechanical type with electrical output, or is of a more recent electronic design handling multiple pump components, a control valve, for example, that has not been properly adjusted or otherwise malfunctions, creates a potential hazard to a large surrounding area due to the high fluid flow rate and pressure. In current systems a valve failure in one lane may present a hazard to other nearby operating pumping lanes that are served by separate sets of pumps, valves and controllers, because the separate sets of controllers monitoring the lane receive no signals that indicate a problem, and are thereby unaffected by the control commands in the lane with the malfunctioning valve. The unaffected lane will continue to operate normally under the hazardous conditions presented by the problem lane.
In systems of current art, the preset values and parameters for loading assume that all of the valves, meters, and other equipment are adjusted, tuned and functioning properly. Another problem is presented, however, in such systems because an overfill condition is possible when a control valve is out of adjustment or does not function properly for whatever reason. For example, when a driver of a tank vehicle enters data into the preset interface, the amount of product to be transferred to a given compartment, for example, the amount is based on the known capacity and overfill sensing point of the destination compartment. If an error is made when a driver enters such preset data, or a control valve that is out of adjustment is not known by the preset, the monitoring and control system may not be able to shut down the pump and valve quickly enough to avoid a spill, once the overfill signal from the probe is received.
Another problem is presented in the area of leakage detection for control valves in systems of current art utilizing an electronic preset. For example, if recent maintenance or electronic board replacement has been performed on the preset, and the preset has not been properly reconfigured to provide the correct alarm when leakage occurs, the leakage, whether intentional or accidental in nature, may not be detected, resulting in product loss.
For safety reasons it is highly desirable in a petroleum or petrochemical product storage and transfer operation to have the capability of globally shutting down pumping and loading operations as quickly as possible if a hazardous condition such as overfill or static ground loss exists. It is also desirable to be able to detect a slow leak in one pump in a set of several operating pumps which are monitored and controlled by the same monitoring and controlling units set, particularly when an electronic preset is not properly reconfigured for providing a leakage alarm signal to the monitoring and controlling units set.
What is clearly needed is a fail-safe method and apparatus for monitoring and controlling various critical aspects of pump and valve operations, having global control capability in both the storage and delivery systems, and providing such controls in much less time than is achievable utilizing current monitoring and controlling systems. Such an improved method and apparatus provides comprehensive, centralized interpretation of operational pulsed signals, verifies static ground, detects product overfill conditions or leakage at various rates, and provides increased visibility to management when a problem in the pumping or delivery system occurs. Such an improved monitoring and controlling apparatus is also capable of continually monitoring several individual meter pulses and pump commands simultaneously, and is compatible with most modem electronic monitoring and control systems currently employed in the field, and can also be configured to be compatible with a variety of other modern monitoring and control systems. Such improved method and apparatus is described below in enabling detail.